Detection or sensing systems have been developed for use with various kinds of manufacturing equipment and power tools. Such detection systems are operable to trigger a reaction device by detecting or sensing the contact of some appendage of an operator with some part of the equipment. For example, capacitive contact sensing systems in table saws that are known to the art detect contact between the operator and the blade, and a reaction device, such as a brake or blade withdrawal device, either halts motion of the blade or removes the blade from contact with the human.
Existing detection systems are generally configured to identify contact between a moving part of the power tool, such as a saw blade, and an appendage or other part of the human body before halting the motion of the blade. The existing systems detect either direct contact with the human appendage, or extreme proximity to the human appendage through capacitive coupling at distances of no more than a few millimeters. Given the minimal detection distances, the existing systems often require high-precision mechanisms to halt a moving saw blade or other implement in a very short time period, such as within 1 millisecond. In light of these deficiencies, improvements to detection systems that enable identification of potential contact between a human appendage and a moving implement in a power tool without requiring direct contact between the appendage and implement would be beneficial.